CVE-2026-52935 xfrm: espintcp: do not reuse an in-progress partial send
A race condition in the Linux kernel's espintcp module allows out-of-bounds reads by reusing in-progress partial send state, potentially leading to memory corruption.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-52935?
CVE-2026-52935 is a high-severity memory corruption vulnerability in Linux kernel, published on 24 Jun 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
xfrm: espintcp: do not reuse an in-progress partial send
espintcp keeps a single in-flight transmit in ctx->partial. Before building a new sk_msg, espintcp_sendmsg() first tries to flush that state through espintcp_push_msgs().
For blocking callers, espintcp_push_msgs() may return success even when the previous partial send is still pending. espintcp_sendmsg() would then reinitialize emsg->skmsg and reuse ctx->partial while the old transfer still owns that state.
Do not rebuild the send message when ctx->partial is still in progress. If espintcp_push_msgs() returns with emsg->len still set, fail the new send instead of overwriting the live partial state.
This is a memory-safety fix: reusing the live partial-send state can leave a stale offset attached to a new sk_msg and lead to an out-of- bounds read in the send path.
tcp_sendmsg_locked() already handles waiting for send buffer memory, so the fix here is just to preserve espintcp's one-message-at-a-time transmit state.
Which versions are affected by CVE-2026-52935?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-52935?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-52935 being exploited?
There is no known exploitation of CVE-2026-52935 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-52935, DEBIAN-CVE-2026-52935, GHSA-9xww-vmqg-jh2q, ROOT-OS-DEBIAN-11-CVE-2026-52935, ROOT-OS-DEBIAN-12-CVE-2026-52935, ROOT-OS-UBUNTU-2204-CVE-2026-52935 and 2 more.